1. Field of the Invention
The present invention can be classified to air traffic control, and particularly to a track prediction method in combined radar and ADS surveillance environment.
2. Description of the Related Art
As air traffic grows rapidly (about 10% per year), current air traffic control system cannot handle it efficiently. To solve the accompanying problems, e.g., rising operational cost and arrival time delay, the International Civil Aircraft Organization (ICAO) established a FANS (Future Air Navigation Systems) committee to study and propose new techniques. FANS proposed new Communication, Navigation, Surveillance (CNS) techniques in 1991 to support future Air Traffic Management (ATM). Among these techniques, ADS-A (Automatic Dependent Surveillance-Addressing) and ADS-B (Automatic Dependent Surveillance-Broadcast) are new techniques for Surveillance.
Since the time interval between two successive ADS-A reports is too long (about 15 to 30 minutes in average), current air traffic control system must be able to predict ADS-A equipped aircraft position in future combined radar and ADS surveillance environment to increase safety. The present invention provides a way to satisfy this requirement.
The object of the present invention is to provide a track position prediction method in combined radar and ADS surveillance environment. The proposed method uses Kalman filter to predict the aircraft position when it receives radar reports. If only ADS-A reports of an aircraft are received, the proposed method use (A)-(F) to predict this aircraft""s position: (A) suppose an aircraft is at position P0, request the aircraft to report its next two way-points P1 and P2. (B) Select turning points Q1 from {overscore (P0P1)} and Q2 from {overscore (P1P2)}; the length of {overscore (P1Q1)}, is equal to that of {overscore (P1Q2)}. (C) At the bisector of {overscore (Q1Q2)}, select various dividing points ci (i=1, . . . g). (D) Use Q1, Q2, slop of {overscore (Q1Ci)}, and slope of {overscore (CiQ2)}, plot Hermite curves Ti connecting Q1 and Q2. (E) The predicted aircraft positions are {overscore (P0Q1)}, Td, {overscore (Q2P2)}, where dxcex5[1,g] is pre-determined by the controller. (F) If an ADS-A report is received before the aircraft passes through P2, the predicted positions will be adjusted accordingly.
The various objects and advantages of the present invention will be readily understood in the following detailed description.